Physical characteristics:
Wolf weight and size can vary greatly worldwide. In general, height varies from 0.6 to 0.95 meters (24 to 37 in) at the shoulder. Wolf weight varies geographically; on average, European wolves may weigh 38.5 kilograms (85 lb), North American wolves 36 kilograms (79 lb), and Indian and Arabian wolves 25 kilograms (55 lb). Though rarely encountered, extreme specimens of more than 77 kilograms (170 lb) have been recorded in Alaska, Canada, and the former Soviet Union. The heaviest recorded gray wolf in North America was killed on 70 Mile River in east-central Alaska on July 12, 1939 and weighed 79 kilograms (170 lb), while the heaviest recorded wolf in Eurasia was killed after World War II in the Kobelyakski Area of the Poltavskij Region in the Ukrainian SSR, and weighed 86 kilograms (190 lb). Grey wolves are sexually dimorphic, with females in any given wolf population typically weighing 20% less than males. Females also have narrower muzzles and foreheads; slightly shorter, smoother furred legs; and less massive shoulders. Gray wolves can measure anywhere from 1.3 to 2 meters (4.3 to 6.6 ft) from nose to the tip of the tail, which itself accounts for approximately one quarter of overall body length.

Gray Wolf skeleton Gray wolves rely on their stamina rather than speed for hunting. Their narrow chests and powerful backs and legs facilitate efficient locomotion. They are capable of covering several miles trotting at about 10 kilometers per hour (6 mph), and have been known to reach speeds approaching 65 kilometers per hour (40 mph) during a chase. One female gray wolf was recorded to have made 7-meter (23 ft) bounds when chasing prey.

Gray wolf paws are able to tread easily on a wide variety of terrains, especially snow. There is a slight webbing between each toe, which allows them to move over snow more easily than comparatively hampered prey. Gray wolves are digitigrade, which, with the relative largeness of their feet, helps them to distribute their weight well on snowy surfaces. The front paws are larger than the hind paws, and have a fifth digit, the dewclaw, that is absent on hind paws. Bristled hairs and blunt claws enhance grip on slippery surfaces, and special blood vessels keep paw pads from freezing. Scent glands located between a wolf's toes leave trace chemical markers behind, helping the wolf to effectively navigate over large expanses while concurrently keeping others informed of its whereabouts. Unlike dogs and western coyotes, gray wolves have a lower density of sweat glands on their paws. This trait is also present in Eastern Canadian Coyotes which have been shown to have recent wolf ancestry. Wolves in Israel are unique due to the middle two toes of their paws being fused, a trait originally thought to be unique to the African Wild Dog.

Genetic research has shown that black furred wolves owe their colouration to a mutation that first arose in domestic dogsWolves have bulky coats consisting of two layers. The first layer is made up of tough guard hairs that repel water and dirt. The second is a dense, water-resistant undercoat that insulates. The undercoat is shed in the form of large tufts of fur in late spring or early summer (with yearly variations). A wolf will often rub against objects such as rocks and branches to encourage the loose fur to fall out. The undercoat is usually gray regardless of the outer coat's appearance. Wolves have distinct winter and summer pelages that alternate in spring and autumn. Females tend to keep their winter coats further into the spring than males.

Gray wolves molt some of their coats in late spring or early summerFur coloration varies greatly, running from gray to gray-brown, all the way through the canine spectrum of white, red, brown, and black. These colors tend to mix in many populations to form predominantly blended individuals, though it is not uncommon for an individual or an entire population to be entirely one color (usually all black or all white). With the exception of Italy, in which black wolves can constitute 20-25% of the entire population, melanistic wolves rarely occur outside the North American continent. According to genetic examinations, the black coat colour is based on a mutation that first arose among domestic dogs and later migrated into the wolf-population via interbreeding. A multicolor coat characteristically lacks any clear pattern other than it tends to be lighter on the animal's underside. Fur color sometimes corresponds with a given wolf population's environment; for example, all-white wolves are much more common in areas with perennial snow cover. Aging wolves acquire a grayish tint in their coats. It is often thought that the coloration of the wolf's pelage serves as a functional form of camouflage. This may not be entirely correct, as some scientists have concluded that the blended colors have more to do with emphasizing certain gestures during interaction.

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